“I don’t think radiation and pharmaceuticals can be filtered out.”
Any industrial reverse osmosis system will easily do that without a sweat. For one thing, the water itself isn’t “radioactive”, only the dissolved minerals or suspended particulate matter. RO systems filters everything out down to the molecular level, which is how even the dissolved minerals are removed.
I once observed a demonstration by nuclear scientists at a U.S. university who dipped their coffee-making water right from the tank of a small water-immersed research nuclear reactor they operated, explaining it was the purest water possible because of the filtering that was used.